We have already
considered 2nd declension nouns and 1st declensions
nouns. Now we will consider 3rd declension nouns.

The 3rd declension is
more varied than the 1st and 2nd declensions. This is
true in terms of form and also in terms of gender. In
terms of gender, remember that 2nd declension nouns
are usually masculine or neuter and 1st declension
nouns are usually feminine. But in the 3rd
declension, no particular gender is dominant. And in
terms of form, at first glance it may seem that there
is very little consistency to the case and number
endings found in the 3rd declension. But closer
examination will reveal two basic patterns (with
variations) for 3rd declensions.

One variation often
seen in 3rd declension nouns has some similarity to
the 2nd and 1st declension endings you have already
learned. Remember that in Course
1, lesson 3,
we identified the true masculine 2nd declension
endings as ς, ο, ι, ν, etc. The "endings" ος, ου, ῳ, ον, are actually the final stem
vowel of the 2nd declension (the omicron
declension) in combination with the true endings.
Similarly, the 1st declension endings α, ας, ᾳ, αν, etc. are actually the final
stem vowel in combination with a similar set of true
endings. Compare these true masculine 2nd declension
endings and the true 1st declension endings with one
pattern of endings frequently seen in 3rd declension
nouns:

Another word that
follows this same pattern with some variation is ἄρχων, -οντος, ὁ, ruler. This word is
especially important because its endings are exactly
those that we will see in the present active
participles of the masculine gender. Memorize
the declension of this noun.

singular

plural

The
stem is actuallyἄρχοντ-, but
in the nominative and vocative singular,
the τ drops
out and the ο lengthens
to ω.

In the dative plural,
dental τ drops out
before σ, the ν also drops out,
and there is compensatory lengthening
of the exposed stem vowel, ο, to ου.Also note
the moveable ν in the dative
plural.

Chapters 13 and 14 in
your text book show several 3rd declension nouns
fully declined. Those in chapter 13 are either
masculine or feminine and follow some variation of
the pattern described above. Those in chapter 14 are
neuter and follow another pattern. The table below
shows the two basic patterns, including variations
you can expect to see.

3rd Declension Endings

masculine or feminine
ch. 13 in your text book

neuterch. 14 in your text
book

singular

nom.

ς,
none

none

gen.

ος

ος

dat.

ι

ι

acc.

α, ν

none

voc.

ς,
none

none

plural

nom.

ες

α

gen.

ων

ων

dat.

σι(ν)

σι(ν)

acc.

ας

α

voc.

ες

α

Various contractions,
omissions, and vowel lengthenings occur as these
endings are attached to nouns with various stem
endings. There is a good discussion of these things
in chapters 13 and 14 of your text book, along with
illustrations of the various patterns with which you
need to become familiar. Study these chapters
carefully.